made the lemon poppy seed from "cake bible" by rose levy b. The height was not as high as her picture. Also, the hump on top flatten as it cooled. What am I doing wrong? am I not aerating/mixing it enough? the recipe uses 1.5 c cake flour and 13 tbsp butter, 3/4 tsp baking powder, 3 eggs, 3/4 c sugar..etc.